Peel the oranges (remove as much of the white pith as possible) and cut crosswise into thin slices.

Remove the hard bottom part of the fennel bulbs and discard, cut the fennel into thin slices.

Peel the red onion, cut into thin slices.

Place orange, fennel and onion slices into a large bowl, season with salt and pepper and drizzle with olive oil. Leave to stand for at least 30 minutes or up to a few hours at room temperature, mixing couple of times.

To serve, place some salad leaves (cos or lamb's lettuce) onto a serving plate, top with salad, including any juices.